I would not be so sure about your first statement. The 28-300 L is now 10 years old. 150-600mm

Given the size & zoom range of this lens, there is no way in hell this Tammy can match 28-300 L optics ... if it is better than the 28-300 L, I will give you my Tamron 24-70 f/2.8 VC for free (excluding the cost of shipping out to you) and I mean it.

Deal

You just put yourself in a very dangerous situation, since "optical performance" can be intended in a number of very ambiguous ways - e.g. contrast, sharpness, CA, bokeh, fringing, etc etc

No problemo sir ... if this Tamron beats the Canon EF 28-300 L IS in any 3 (which must include sharpness) of the 5 parameters you've mentioned here i.e. Contrast, Sharpness, CA, bokeh, fringing, I promise to give you my Tamron 24-70 f/2.8 VC for free (provided you pay for the shipping costs).

Given the size & zoom range of this lens, there is no way in hell this Tammy can match 28-300 L optics ... if it is better than the 28-300 L, I will give you my Tamron 24-70 f/2.8 VC for free (excluding the cost of shipping out to you) and I mean it.

Canon 28-300 weighs 1670 g while Tamron weighs 540 g. I will never consider Canon's offering regardless of its performance.

I would not be so sure about your first statement. The 28-300 L is now 10 years old. 150-600mm

Given the size & zoom range of this lens, there is no way in hell this Tammy can match 28-300 L optics ... if it is better than the 28-300 L, I will give you my Tamron 24-70 f/2.8 VC for free (excluding the cost of shipping out to you) and I mean it.

Deal

You just put yourself in a very dangerous situation, since "optical performance" can be intended in a number of very ambiguous ways - e.g. contrast, sharpness, CA, bokeh, fringing, etc etc

No problemo sir ... if this Tamron beats the Canon EF 28-300 L IS in any 3 (which must include sharpness) of the 5 parameters you've mentioned here i.e. Contrast, Sharpness, CA, bokeh, fringing, I promise to give you my Tamron 24-70 f/2.8 VC for free (provided you pay for the shipping costs).

BUT if the IQ is similar to the 70-300 IS USM, then this could be a lense that causes a bit of trouble in the market place.

If you are referring to 70-300 IS, then I am pretty confident that this Tamron lens will be at least similar if not better.But if you are talking about 70-300 L IS, then I don't think this Tammy be anywhere close ... I would like to end being wrong here but I'm pretty sure it cannot match the 70-300 L ISAlso, looking at the size vs zoom range, it seems like it is aimed at "tourists" who carry their full frame cameras, but would appreciate and be OK with an all-in-one lens that provides decent enough photos without expecting too much from it. I count myself in that category when I go on guided tours. I hope its not like the previous Tamron 28-300 VC lens, I owned it briefly and sold it off real quick due to its poor construction and clunky noise.

I was referring to the non-L. I agree, a 3rd party non-special lens couldn't (probably) get near the L, but might just shade the IS USM non-L.

I tend to shoot with L series zooms, but as a stroll-around this looks very attractive due to the zoom range, reach, the fact that it'll be a lot lighter than the 70-200 2.8 IS v2 I use and a lot less attractive to those wanting to nick your camera gear

This is great news, only I'm left wondering - it's already Feb and so far in this "year of the lens" we've got two Tamron superzooms and a Sigma 50 Art on the way. So, where's the Canon lenses we were told about??

This is great news, only I'm left wondering - it's already Feb and so far in this "year of the lens" we've got two Tamron superzooms and a Sigma 50 Art on the way. So, where's the Canon lenses we were told about??

The Canon Jedi's will come out and say "These aren't the zooms you were looking for"

Given the size & zoom range of this lens, there is no way in hell this Tammy can match 28-300 L optics ... if it is better than the 28-300 L, I will give you my Tamron 24-70 f/2.8 VC for free (excluding the cost of shipping out to you) and I mean it.

Canon 28-300 weighs 1670 g while Tamron weighs 540 g.

That was the only reason why I did not buy a Canon 28-300 L IS ... instead I went with the Tamron version but did not like it at all and sold it as fast as I could.

For me, it is not very wise 28-300mm on full frame. It would be much more useful if Tamron makes a 24-200mm F3.5-5.6 VC. Could be more appropriate weight and size, and would promote the image quality and autofocus.

As a few others here have shared, I've also tried the current version of the Tamron 28-300 zoom and quickly got rid of it due to poor image quality. I convinced myself that a used one for a good price would make the IQ acceptable, no go.

Personally I like the idea of a light all-in-one travel (vacation) zoom. The 28-300L has impressive IQ for it's range, but the size and weight just makes it generally prohibitive for me to use it as a travel lens.

Having been burned once with this Tamron, I'll wait until the dust settles and real world reviews are in before I get to worked up.